The simple trick to finding cheaper flights

When looking for cheap flights, you're often told to "shop around" but there is another way to take advantage of airline's airfare fluctuations.

Depending on what airline's website you use, you could save yourself money, or end up spending more money if you're not aware of how airfare systems work.

On the New Zealand website, a ticket for this flight is $59 (Air New Zealand)

Flights on the same route, on the same day can be more expensive on different websites (Air New Zealand)

Airlines need to fill seats which means they may offer discounts or cheaper fares to fill the plane from a more likely market.

However that means prices aren't necessarily the same on return legs.

For example, an Air New Zealand flight from Napier to Auckland on August 18 through its New Zealand website is priced at NZ$59, whereas the same flight on its Australian website was priced at NZ$113.

A flight from Hamilton to Dunedin is available for $144 (Air New Zealand)

However the same flight is considerably more expensive on the Australian website (Air New Zealand)

In another case, a flight from Hamilton to Dunedin on August 8 would cost you NZ$144 if you booked on the New Zealand website. That same flight would cost another NZ$151 if you booked through the Australian website.

However, in rare cases flights booked through Air New Zealand's Australian website were actually cheaper than booking on the New Zealand website. So it pays to try both before buying.

When asked why there were differences, Air New Zealand told Newshub it is "normal practice" due to local customer demand, seat availability and local promotional activity.

Aviation commentators agree it is common practice and there is nothing untoward going on.